The invention relates to ceramic decorating substances with increased color saturation (chroma value C* according to DIN 5033), substantially comprising a zirconium pigment of the host lattice or inclusion type and a glass flux of one or more glass frits, wherein the pigment volume concentration (PVC) is at least 30%. The invention further is directed toward a process for the production of the decoration coloring substances as well as their use, in particular for production of ceramic decorations which are burned above 1000.degree. C., more particularly from 1100 to 1250.degree. C.
Decoration coloring substances for the production of ceramic decorations are known. Conventionally they comprise substantially one or several pigments and a glass flux of one or several glass frits. The decoration coloring substance is formed by intimately grinding the components together (see Ullmann's Enzyklopadie der technischen Chemie, Fourth Edition (1977), Volume 14, pp. 9-10).
The market demands brilliant decorations with the strongest possible coloring power, and decorations burned in high-temperature burning processes are gaining importance. Strict requirements exist for the thermal stability of decoration coloring substances suitable for this purpose. A thermally stable pigment class comprises the so-called zirconium pigments, these being host lattice pigments such as zirconium praseodymium yellow, zirconium vanadium blue and zirconium iron pink, and zirconium inclusion pigments in which coloring crystals, such as in particular cadmium sulfide or cadmium sulfoselenides are included in zirconium silicate (=zircon) (loc. cit. pp. 2-3). The strong coloring power of a decoration coloring substance, thus its color saturation, is specified in the CIE laboratory system (DIN 5033, Part 3) as chroma value C*, wherein C*=(a.sup.2 +b.sup.2).sup.0.5 and, at the correct color shade, should have a maximum value. The C* value can be increased by increasing the pigment volume concentration (pigment in percent by volume in the fused decoration coloring substance), however, there exists interest in increasing the c* value further at a given PVC.
The object of the present invention is to provide a path by which, in a simple manner, the C* value at a PVC of at least 30% can be increased.